U.S. patent application number 12/313496 was filed with the patent office on 2010-05-27 for biofiltration system for odor control.
Invention is credited to Martin Crawford.
Application Number | 20100129895 12/313496 |
Document ID | / |
Family ID | 42196656 |
Filed Date | 2010-05-27 |
United States Patent
Application |
20100129895 |
Kind Code |
A1 |
Crawford; Martin |
May 27, 2010 |
Biofiltration system for odor control
Abstract
The invention involves the creation of a corrosion resistant gas
treatment system comprising a unitary housing subdivided into at
least two internal sections, the only connection between the first
and the following section(s) is a gas only passage channel; the
design allows the simultaneous remediation of contaminants from
multiply contaminated gas streams in which some of the contaminants
require the presence of microorganisms tolerant of widely differing
pH and moisture needs for their reduction. The operation is simple
and very efficient because the absence of fluid communication
between the two sections allows keeping the moisture levels, pHs
and microorganism profiles of the two sections specifically
optimized for the target pollutants in the gas stream.
Inventors: |
Crawford; Martin;
(Stateline, NV) |
Correspondence
Address: |
William S. Bernheim
255 N. Lincoln St.
Dixon
CA
95620
US
|
Family ID: |
42196656 |
Appl. No.: |
12/313496 |
Filed: |
November 21, 2008 |
Current U.S.
Class: |
435/262.5 ;
435/283.1 |
Current CPC
Class: |
B01D 2257/90 20130101;
B01D 53/18 20130101; B01D 2257/304 20130101; B01D 2257/306
20130101; B01D 2257/70 20130101; B01D 53/85 20130101; B01D 2257/406
20130101; Y02A 50/2359 20180101 |
Class at
Publication: |
435/262.5 ;
435/283.1 |
International
Class: |
A62D 3/02 20070101
A62D003/02; C12M 1/00 20060101 C12M001/00 |
Claims
1. A device for treating a multiple contaminant polluted gas stream
to reduce the concentrations of said multiple pollutants by moving
a continuous flow of such a gas stream through a treatment unit
comprising a unitary external shell housing at least two
sequentially placed fluid containing treatment sections that are
separated by an internal pair of intervening partial height walls
to form a first treatment section, and a second treatment section;
said partial height walls having a space between them, and which
said partial height walls being situated with respect to the
external shell in a manner intended to form a gas communication
only channel situated between said first treatment section and said
second treatment section; said treatment unit's external shell
comprising a floor, a roof, a right and a left side wall, a
treatment unit front wall, a treatment unit end wall, a gas stream
inlet assembly piercing said front wall of said treatment unit
through which a multiply polluted gas stream passes into said first
treatment section of said treatment unit; a series of exhaust
stacks projecting upward from a series of matching exhaust ports in
said roof over a gas exit plenum situated at the top of said second
treatment section of said treatment unit through which said treated
gas stream passes out into the environment; said partial height
wall at the rear of said fluid filled first treatment section being
integrally connected with said floor and said side walls of said
treatment unit and extending upwards from said floor to terminate
at a location slightly below said roof of said treatment unit; and,
said second partial wall, being located a short distance to the
rear of said first partial wall and forming an internal front wall
of said second treatment section, being integrally attached to said
roof and said side walls of said treatment unit, but depending
downwards from said roof and terminating at a location slightly
above said floor of said second treatment unit; the staggered tops
and bottoms of which said partial internal walls forming part of a
functional arrangement allowing for passage of said on-flowing gas
stream from said first treatment section to said second treatment
section without fluid transfer between the two said treatment
sections; means existing within said first treatment section to
prevent said first treatment section's partial height rear wall
from acting as a weir as a counter flow moisture stream passes
downward through a media bed containing an appropriate media, said
media in said bed containing microorganisms that remediate some of
the pollutants in said air stream; means existing in said second
treatment section for preventing the fluid in said second treatment
section from passing backwards and up into said open space between
said partial walls as a counter flow moisture stream passes
downward through a media bed containing an appropriate media within
said second treatment section; said media in said second treatment
chamber's treatment bed containing microorganisms that remediate
other classes of pollutants than were remediated in said first
treatment section; means existing for controlling an electrical
power, water delivery and waste water removal array of operational
components of said treatment unit. means existing for separately
monitoring the air pressure differential between the inlet and
outlet sides of said media beds in said first treatment section and
said second treatment section.
2. The Unit of claim 1 wherein the water stream entering said first
treatment section's said treatment bed, has been pre-modified and
stabilized within the pH range of 1.8 to 2.2, by the proportional
pre-mixing of fresh water from an external source with
hyper-acidulated water that has passed through said first treatment
section's said treatment bed and into said sump of said first
treatment section.
3. The treatment unit of claim 1 wherein, the unitary housing is
internally subdivided into more than two treatment sections, a
first treatment section being followed by a series of successive
secondary treatment sections; said successive secondary treatment
sections being separated each from the preceding said successive
secondary treatment section by paired, internal, partial height
walls; said paired partial height walls having a space between
them, and which said partial height walls are situated with respect
to the external shell of said treatment unit in a manner intended
to form a gas communication only channel situated between a forward
situated secondary treatment section and a successor secondary
treatment section; said first wall of any of said pairs of partial
height walls that are separating a pair of said fluid containing
successive secondary treatment sections, being integrally connected
with said floor and said side walls of said treatment unit and
extending upwards from said floor to terminate at a location
slightly below the roof of said treatment unit; and, said second
partial wall of any of said pairs of partial walls being integrally
attached to said roof and said side walls of said treatment unit,
but depending downwards from said roof and terminating at a
location slightly above said floor of said treatment unit; the
staggered tops and bottoms of which said pairs of partial internal
walls form part of a functional arrangement allowing for passage of
said on-flowing gas stream from a forward situated secondary
treatment section to a successive secondary treatment section
without fluid transfer between the two said sections; means
existing within said first treatment section to prevent said first
treatment section's partial height rear wall from acting as a weir
as a counter flow moisture stream passes downward through a media
bed containing an appropriate media, said media in said bed
containing microorganisms that remediate some of the pollutants in
said air stream; means existing in said multiple successive
secondary treatment sections for preventing the fluid in any of
said successor secondary treatment sections from passing backwards
and up into said gas only channel between said partial walls and
thence into the preceding secondary treatment section as a counter
flow moisture stream passes downward through a media bed containing
an appropriate media within said successor secondary treatment
section; said media in said successive secondary treatment beds
containing microorganisms that remediate other classes of
pollutants than were remediated in said first treatment section,
and in certain instances being capable of remediating other classes
of pollutants than were remediated in the immediately preceding
successive secondary treatment section; means existing for
controlling an electrical power, water delivery and waste water.
removal array of operational components of said treatment unit.
means existing for separately monitoring the air pressure
differential between the inlet and outlet sides of said media beds
in said first treatment section and any of the successive secondary
treatment sections.
4. A Process for treating a multiple-contaminant polluted gas
stream by passing said gas stream through a remediation unit
comprising a unitary external shell housing two or more
sequentially placed fluid containing treatment sections. The first
of which pair of treatment sections are separated by an internal
pair of intervening partial height walls to form a first treatment
section and a second treatment section; succeeding treatment
sections, if any, comprising successive secondary treatment
sections, each of which successive secondary treatment sections are
separated by a pair of intervening partial height walls, excepting
a final chamber which said chamber has a full height rear wall;
said process being accomplished by: a. moving a fan driven gas
stream at slightly above ambient air pressure into an inlet
manifold of said first treatment section then into a gas stream
entry plenum of said first treatment section and vertically upwards
through a media bed filled with an appropriately moistened
inorganic medium such as foam or reticulated foam that has been
inoculated with autotrophic microorganisms tolerant of a pH range
of 1.8 to 2.2, which said microorganisms feed on and remove
hydrogen sulfide gas, other sulfides, ammonia, amines and such
compounds from said airstream, thus partially remediating said gas
stream, the while a continuous counterflow moisture stream is
passing downwards through said media bed from sprinklers situated
above said media bed; b. means existing in said first treatment
section to ensure that fluids do not accumulate in a sump section
at the bottom of said first treatment section, thus preventing a
weir action of fluid over a partial height rear wall of said first
treatment section and facilitating the forward and upward movement
of said incoming pollutant laden gas stream; after passing through
said media bed in said first treatment section, said partially
remediated gas stream continues to pass upwards into a combined gas
space/moisturization chamber and thence, driven by the pressure
behind it, next moves over said partial rear-wall of said first
treatment section; said rear wall being integral with a floor and a
pair of side walls, and extending upwards from said floor to a
point located a short distance below a roof of said first treatment
section; c. said partially remediated air stream then passes over
said first treatment section's partial rear wall moving thus into a
gas communication only channel, the rear wall of which said gas
communication only channel comprises the external surface of a
front wall of said second treatment section, or of any of a series
of successive secondary treatment sections, which said front wall
extends downward from said roof of said treatment unit and ends a
short distance above said floor of said treatment unit, allowing
said on-moving gas stream to flow into a gas entry plenum at the
bottom of said second treatment section, or of any of said
successive secondary treatment sections; d. where means in said
second treatment section, or in any successive secondary treatment
section ensures that fluids in said second or said successive
secondary treatment sections do not accumulate and pass backwards
into said gas communication only channel or move upwards into a
media bed of said treatment section and which facilitates the
forward movement of said partially remediated gas stream upwards
vertically through said media bed; which said media bed contains an
organic medium such as granulated carbon, wood chips, other carbon
based media, engineered media, lava rock or such other suitable
media that has been inoculated with heterotrophic microorganisms
tolerant of a neutral or slightly basic pH and which said organisms
serve to remove organic nitrogenous compounds and other residual
compounds from said contaminated gas stream; said media being
continuously fed by a counterflow moisture stream that serves to
further remediate said gas stream; and which said moisture stream
optionally can carry inoculant or other such emendatory elements
into said media bed(s). e. said gas stream having moved upwards
through the properly pH regulated media of said second, or,
successive secondary treatment sections' media bed, next passes
into a combined gas space/moisturization chamber of the second
treatment section and then moves upwards into a gas exit plenum,
finally exiting into the ambient environment via a series of
exhaust stacks that are situated over said second treatment
section; or, in the presence of multiple successive secondary
treatment sections, said airstream passes by the same process from
each said preceding to each said succeeding sections(s) until
reaching the last of said sections and thence moving upwards into
said gas exit plenum, and thence into the ambient environment.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The invention relates to an apparatus and process for
treating air streams to remove pollutants. More particularly it
relates to a system that allows for remediation of multiple
contaminants by contaminant-specific remediation organisms having
differing pH and moisture needs, the continuous flow process being
performed within an internally segmented unitary housing in which
there is no fluid connection between the sectional treatment
chambers.
[0003] 2. Description of the Relevant Prior Art
[0004] Vaporous pollutants, which are frequently toxic or corrosive
or both, are created in a multiplicity of municipal, commercial and
agricultural processes and become part of output airstreams.
Treatment of these output airstreams to strip out the pollutants is
important to human health, to prevent damage to equipment, to
protect the environment and to provide odor control.
[0005] The earliest methods used to deal with these pollutants were
by physical and chemical processes. The physical processes
unfortunately created large amounts of contaminated waste materials
that then had to be dealt with. The chemical treatment methods that
replaced physical decontamination are well established and
reliable, however, they involve the use of hazardous chemicals and
are associated with the need for increased safety features that
increase the footprint and the operating costs of the units.
[0006] These drawbacks led to the development of biological
treatment of air streams that has proven itself to be effective,
safe and cost effective. Such biological treatment systems are
capable of treating high flows of contaminated gas having high
inlet concentrations of pollutants.
[0007] A typical biological treatment system involves passing the
contaminated air stream through an inert, porous media base that
has been inoculated with and supports the growth of specific
microorganisms. The contaminated air passes over the organisms
which feed on and convert the pollutants into innocuous compounds,
thus removing the odor and other undesirable components and
allowing the release of remediated air.
[0008] The whole process taking place within a containment
structure which serves as a unit. In instances where the air stream
contains corrosive gases, the materials used to form the treatment
unit are chosen to be as non-reactive as practical. Issues include
treatment unit size, the need to deal with multiple contaminants
that require different pH and moisture conditions for the support
of the bio-organisms that remediate each of the contaminants and
providing a control system that provides maximal remediation with
minimal complexity.
[0009] Some of the most common air stream contaminants include
hydrogen sulfide, mercaptans, amines and various organic acids.
Hydrogen sulfide gas is toxic and very corrosive and is found in
places as diverse as municipal sewage and sewer lines, oil well
drilling locations, wood processing plants, and various other
municipal and industrial processes in which elemental sulfur comes
into contact with organic materials. This is the gas associated
with the smell of `rotten eggs`. It is very toxic and can kill by
asphyxiation, or by explosion.
[0010] A very effective method for treating hydrogen sulfide is to
pass the air containing hydrogen sulfide through a highly porous,
chemically inert media that is being bathed in water at a pH in the
range of 1.8-2.2. Under these conditions a biological culture can
be made to grow on the media and the cultured organisms will use
hydrogen sulfide as a food source, converting the hydrogen sulfide
to sulfuric acid using oxygen present in the air.
[0011] Organic Compounds other than hydrogen sulfide can be treated
by moving the air containing these organic compounds through a
highly porous, chemically inert media at a neutral or mildly
alkaline pH while ensuring that the air is humidified and the media
is kept moist through supplemental irrigation. Under these
conditions a biological culture that will use these organic
compounds as a food source can be made to grow on the media and
convert those compounds to carbon dioxide and other by-products
using oxygen present in the air.
[0012] Systems that try to simultaneously treat gas streams
containing hydrogen sulfide as well as other organic compounds run
into the following problem: oxidation of the hydrogen sulfide
component of these complex air streams yields a by-product of
sulfuric acid that interferes with the development of the
biological substrate necessary for the treatment of the non
hydrogen sulfide components of the air stream.
[0013] Oxidation of hydrogen sulfide takes place primarily at low
pH conditions, and requires the use of autotrophic Thiobacillus
bacteria. The bulk of the other contaminants commonly encountered
in mixed contaminant airstreams require the use of heterotrophic
bacteria at close to neutral pH conditions. The presence of both
autotrophic and heterotrophic bacteria within a single treatment
chamber causes a competition between the various bacteria at the
required operating conditions. This in turn leads to reduced
efficiency in the system because the non-separated fluid sections
do not lend themselves to optimizing the pH in the sections of the
treatment unit that are dealing with compounds requiring acid vs.
neutral or base tolerant strains of microbial flora. It also leads
to the need for using an increasingly complex system of trying to
balance the pH of the water to the needs of the differing bacterial
colonies within the treatment unit.
[0014] Bonnin et al., in U.S. Pat. No. 5,858,768, describe a system
for the biodegradation of sulfurous compounds in combination with
the physical/chemical elimination of organic nitrogenous compounds.
The system is not continuous for the removal of both sets of
pollutants, and though alteration of pH is provided for, the pH
parameters described do not provide optimal target pH levels for
either the acid or the base environment dependent microorganisms,
thus likely leading to less efficiency in clearing Hydrogen sulfide
gas. Like Horn, U.S. Pat. No. 5,869,323, Koers in U.S. Pat. No.
5,445,660 describes a system in which the polluted air is passed
through at least two or more separate housings for purposes of
treating pollutants requiring environments of differing pH and
moisture for the biologically active components in the chambers.
Needing multiple housings increases the cost and the number of
connecting elements, pumps, seals and monitoring devices needed and
thus would seem to create a less cost effective approach. Parker,
et al in U.S. Pat. No. 7,276,366 describe a vertical treatment unit
having two media containment sections within a unitary housing.
However, the vertically stacked media sections are separated only
by the perforated floor of the upper section. Contaminated air
enters through an inlet at the bottom of the unit and passes
sequentially upwards through both media bed sections and thence out
an exhaust stack. Water for moistening the media bed, carrying in
microorganisms or altering the pH can be introduced atop either the
top section or the lower section in a reverse flow direction to the
movement of air in the unit. However, any fluid entering the top
section must percolate into and through the lower bed in order to
enter the sump and exit the system, this raises the pH in the lower
section. A complex, computer controlled system is required to
periodically, and for a predetermined run time, alternate between
passing fresh irrigating water, or recycling acidifying water from
the sump into one or the other or both bed sections in an attempt
to maintain pH in the 1.8-2.2 range for optimal clearance of
Hydrogen sulfide in the lower ("Bioscrubber") section. The upper
("Biofilter") section pH being controlled in a similar manner such
that it suits more alkaline loving microorganisms. Having a fluid
connection between the bioscrubber and biofilter sections of the
treatment unit leads to increased complexity of the control system
and decreased specificity of the pH levels for optimal colonization
of the microorganisms in the two sections of the treatment unit. As
with any such media bed system, the vertical height is limited by
the need to prevent compaction of and channel formation within the
media beds. A series of these vertical units would be needed to
handle larger volumes of contaminated air, resulting in the need
for additional computer control systems which of course leads to a
higher cost for the system.
[0015] Past designs for systems capable of remediating air streams
containing mixed pollutants have suffered from the need to use
multiple units for large scale operations and that led to increased
installation costs. The fluid connection between the sections of
the treatment units created alterations of pH that reduced the
units' decontamination cost-efficiency. Some have required complex
control systems to try and maintain proper pH, moisture levels and
microbial populations tolerant of the pHs of the varying pollutants
in the air stream because of the fluid communication between the
internal sections of the unit.
Statement of the Objectives
[0016] Accordingly, it is an objective of this invention to provide
a unitary housing treatment Unit having no fluid connection between
its two or more, separated, fluid containing, internal treatment
chambers.
[0017] A further objective is to provide a unitary, corrosion
resistant, housing that can be created having the structural
strength allowing for its use in large commercial and municipal
reactors, yet also having a flexibility of design allowing for use
in small sized reactors.
[0018] Another objective is to provide a treatment unit that allows
optimal control of pH, moisture levels and microbial population
purity within the separated internal sections of the structure that
are intended to separately and sequentially remediate Hydrogen
sulfide, which requires microorganisms that are very acid tolerant,
and other pollutants such as mercaptans, amines and various organic
acids that are dealt with by microorganisms that can only flourish
at neutral or basic pH levels.
[0019] Another objective is to provide a system that is easily
managed and largely self-regulating thus reducing operating
costs.
SUMMARY OF THE INVENTION
[0020] The invention involves the creation of a unitarily housed
air treatment system for the remediation of mixed air stream
pollutants that embodies at least two separate treatment chamber
sections, at least one of which requires the presence of
microorganisms tolerant of a highly acidic pH while another or
other sections require a neutral or basic pH. The design allows
complete independent control of media bed pH, moisture levels, and
microorganism population types within the two treatment chamber
sections. The air pathway is from below upwards with countercurrent
moisture application from above down in both treatment chambers.
The only connection between the first and the following section(s)
is an air-communication only channel which allows air that has
passed through the more acidic treatment chamber wherein Hydrogen
sulfide and like products are reduced, to move into the Unit's
further chamber(s) without altering the moisture and pH thereof.
Sensors and regulators are used to keep pH, moisture levels and
rate of flow within predetermined parameters in both treatment
chambers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1. Presents a longitudinal cross sectional view of a
treatment unit. The drawing is not to scale, the vertical component
having been expanded for clarity.
[0022] FIG. 2 Presents a transverse sectional view of the same unit
looking down from above, but with the roof section removed. The
drawing is not to scale, especially as regards the width which is
exaggerated in respect to the length of the unit
[0023] FIG. 3. Presents a detail of the air-communication only
channel that separates the first treatment-chamber ("bioscrubber")
and second treatment-chamber ("biofilter") sections of the
treatment unit.
[0024] FIG. 4 Presents a diagrammatic representation of the control
system, electrical and water supplies and the waste water removal
system of the treatment unit.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0025] Further objectives advantages and novel features of the
invention will be apparent to those skilled in the art from the
following detailed description when taken in conjunction with the
accompanying drawings illustrating a preferred embodiment of the
invention.
[0026] As seen in FIG. 1, the invention involves the creation of a
unitarily housed gas stream purification treatment unit ("Unit") 1
fabricated from fiber glass reinforced plastic (FRP), or other
chemical resistant material such as fiberglass, plastic, stainless
steel; the Unit 1 being internally divided into at least two
treatment chambers having no fluid connection, a bioscrubber
("Scrubber") section 100 and a biofilter ("Filter") section 200
that are connected by a gas communication only channel (Gas
Channel) 40;
[0027] Gas Channel 40 creates a non-fluid connection between
Scrubber and Filter sections 100 and 200; the totality of the
treatment Unit 1 externally comprising a front wall 110, a Scrubber
section 100 roof 109; a dome shaped Filter section 200 roof 201, a
rear wall 202 and a floor 203; the whole being fabricated of FRP,
or of FRP reinforced by steel support members (none depicted) that
are sealed away from the internal chambers of said Unit by being
coated with a chemical resistant material when issues of size and
weight dictate such reinforcement. Note: a pair of side walls 42
FIG. 2 and 43 FIG. 2 are not indicated as such in this view.
[0028] Continuing with the view shown in FIG. 1, a contaminated gas
stream enters the Scrubber section 100 via the driving force of a
fan (not shown), the gas stream flows in the direction indicated by
the arrow 41 and thus into an inlet flange assembly 101 that is
affixed to the Scrubber section 100 front wall 110; the gas then
moves into a gas stream entry plenum 102; a perforated plate 112
delineates the top boundary of the plenum 102 and also serves as
the bottom limit of a media section 103; the lower limit of the gas
stream entry plenum 102 is formed by a perforated plate 113 which
also serves as the top boundary of a sump 114 of Scrubber section
100; the gas stream next moves up into media bed section 103 after
which it passes into a moisturization chamber section 107 where it
passes beneath a series of sprinklers 105 located on a set of water
lines 106 that are attached to a series of FRP cross braces 108
which in turn are affixed to the undersurface of the roof 109 of
Scrubber section 100;
[0029] The gas stream, now cleansed of some contaminants moves up
and over the Scrubber section 100 rear wall 111, which will be
noted extends below to the floor 203 and ends above at a short
distance beneath the Scrubber section 100 roof 109, forming the
front wall of the Gas Channel 40; a front wall 204 of the Filter
section 200 forms the rear wall of Gas Channel 40; the Filter
section 200 front wall 204 depends down from the Filter section 200
domed roof 201 and ends below at a perforated floor plate 205.
[0030] Perforated floor plate 205 serves as both the base of the
Filter section 200 media bed 206 and as the top plate of the Filter
section 200 sump section 217; the Filter section 200 sump 217 is
drained by overflow drain 216 that allows water collected therein
to be evacuated such that the sump 217 contains a headspace which
serves as an entry plenum into which the gas stream being treated
passes from Gas Passage 40.
[0031] Following which the gas stream moves up through perforated
floor plate 205 into the Filter section 200 media bed section 206,
then up into a moisturization chamber section 207 where supply
water is added by a series of sprinklers 208 attached to a water
inlet line array 209 FIG. 1 (best seen in FIG. 2) that is supported
along a pair of longitudinal FRP supports 210 which in turn are
affixed to a series of FRP cross supports 211 that are attached to
the Filter section 200 perforated, internal top plate 212.
[0032] The Filter section 200 perforated internal top plate 212
also serves as the floor of a gas stream exit plenum 213 where the
purified gas collects and then moves up into a set of exhaust
stacks 214 and finally into the ambient air mass.
[0033] Scrubber section 100 media bed section 103 contains an inert
media 104 (cross hatching), such as conventional foam, reticulated
foam, plastic or other such acid resistant synthetic materials;
whichever media material is selected for use, that material is
inoculated with and serves as the support substrate for colonies of
autotrophic micro-organisms that feed on Hydrogen sulfide gas, the
primary component of the gas stream removed in Scrubber section
100; less quantitavely prominent organic sulfides, ammonia, amines
and such compounds are also removed in the scrubber 100 media bed
103.
[0034] Filter section 200 media bed section 206 contains an inert
medium 215 (cross hatched area) such as granulated carbon, other
carbon based media, wood chips, engineered media, lava rock or
other such media that are inert to mildly alkaline solutions;
whatever the media type selected for use, the media material is
inoculated with and serves as the support for heterotrophic
microorganisms that thrive in a neutral to mildly alkaline
environment. These heterotrophic organisms digest organic
nitrogenous compounds and other residual contaminants, thus
removing them from the gas stream.
[0035] Note, the use of the terms "Scrubber" and "Filter" in the
preceding and following text refers to two sections of the
treatment Unit 1 that are designed to operate on differing
component compounds of a multiply contaminated gas stream. Both use
microorganisms colonized on base media for purposes of gas stream
remediation. Neither section relies on a physical "filtration"
system of purification. In all instances, the term "Scrubber"
refers to the first air treatment chamber, which is kept at a low
pH range, optimally pH 1.8 to 2.2, whereas the term "Filter" refers
to the second air treatment chamber which is kept at a neutral to
mildly alkaline pH range.
[0036] The microorganisms 104 and 215 respectively in the Scrubber
and Filter 100 and 200 media bed sections 103 and 206 require a
moist environment; moisturization is provided by sprinkler sets 105
and 208, the flow of water from which creates a counterflow
movement of water down though the media beds 103 and 206;
initially, the water entering both the moisturization chambers 107
and 207 is fresh inlet water from an outside source (not shown);
that water having first been conformed to a specific pH range by a
control system (not shown) that will be described later and
presented diagrammatically in FIG. 4.
[0037] pH regulated water from an external source continues to be
the only moisturizing water used in Filter section 200 as long as
the treatment Unit 1 is in operation. However, the digestion of
hydrogen sulfide gas in the Scrubber section 100 leads to the
formation of Sulfuric acid that mixes with and increases the
acidity of the water to an undesirable pH as it passes down though
the Scrubber section 100 media bed 103; this problem is corrected
as follows: the hyper acidulated water passes down through air
plenum 102 and then through perforated plate 113 into sump 114;
some of the hyper acidulated water passes out of the system through
a scrubber overflow drain 116; fresh water from an external source
(not shown) is mixed in with the remaining hyper acidulated water
in Scrubber section 100 sump 114 in order to bring the water into
the proper pH range of 1.8 to 2.2, following which pH modification,
the water is re-used in the Scrubber section 100 moisturization
chamber 107.
[0038] No water is recirculated through the Filter section 200
media bed 206 which requires a neutral to alkaline pH and the water
flowing into sump 217 passes through overflow drain 216 and is
disposed of via the external drain system (not shown).
[0039] A Scrubber section 100 drain 117 (best seen in FIG. 2) is
controlled by a valve 118 FIG. 2; when fully emptying Scrubber 100
is indicated, water exiting this drain passes into a waste water
line 119 FIG. 2 and thus out of the system.
[0040] When viewed from above as in FIG. 2, some further aspects of
the invention, and other spatial aspects of features seen in FIG. 1
can be viewed. A brief review of the dynamics of the working of the
system follows for the purpose of orienting the process within this
view looking down into the Unit 1 with the roof sections 109 FIG. 1
and 201 FIG. 1 removed.
[0041] Thus, in FIG. 2 side walls 42 and 43 of the treatment Unit 1
are now seen completing the perimeter shell along with front wall
110 and rear wall 202; a recirculation pump 120 is affixed to the
Scrubber section 100 recirculation drain 115; a recirculation
system water line 316 (best seen in FIG. 4) passes out from
recirculation pump 120 and forms part of a recirculation and
control system that will be described later.
[0042] A contaminated gas stream enters from a source 41 and after
passing from a contaminated gas stream inlet duct (not shown) that
is attached to a flange 50, the gas passes through air inlet 101
and thus through the Scrubber section 100 as described prior. Gas
Passage 40 is visible between the Scrubber section 100 rear wall
111 and the Filter section 200 front wall 204.
[0043] The topmost layer of the moisturizing support and delivery
arrangement comprises: two cross braces 108 in the Scrubber section
100, and six cross braces 211 in the Filter section 200. In Filter
section 200, longitudinal support beams 210 are affixed beneath the
six cross braces 211 and the water line 209, comprising a central
pipe with eight laterals, each of which terminates in a sprinkler
208 at both ends, is suspended beneath the longitudinal support
beams 210 at each lateral offshoot of the sprinkler line 209.
[0044] The moisturizing support and delivery arrangement in the
scrubber section 100 differs in that no longitudinal support beams
are needed because of its short depth. The Scrubber section 100
water pipe 106 with its sprinklers 105 is suspended solely from the
paired cross braces 108 to which it is attached.
[0045] For purposes of further orientation in FIG. 2, three circles
representing the tops of exhaust stacks 214 that are spaced above
the roof (not shown) are seen spaced along the longitudinal center
of the Filter section 200; the Filter section 200 overflow drain
216 located in the floor 203 is seen centrally at the rear of the
filter section 200.
[0046] Gas Channel 40, as shown in greater detail in FIG. 3
provides a better understanding of the invention's method of
allowing a unitary housing to contain two separate fluid-containing
gas stream treatment chambers each of which operates at a separate
pH level without fluid connection between the two chambers.
[0047] Gas Channel 40 is formed anteriorly by the Scrubber 100 back
wall 111 that is integrally attached to the floor 203 and ends
above at a distance short of the roof 109; back wall 111 is
integrally attached laterally to the right and left side walls 42
and 43 of Unit 1.
[0048] Contaminated gas enters the Scrubber section 100, and after
passing through media section 103 and into moisturization chamber
107 as partially treated gas, the gas stream then follows the
pathway shown by the arrow 44 and passes over the Scrubber back
wall 111 and then downwards through Gas Channel 40.
[0049] The media bed 103 of Scrubber 100 terminates short of the
top of the Scrubber section 100 back wall 107, and in conjunction
with the Scrubber 100 overflow drain 116 that prevents excess
buildup of exiting water, helps to insure that no water flows from
the Scrubber section 100 into the Gas Channel 40 despite the
constant counterflow of water entering the Scrubber 100.
[0050] Filter section 200 front wall 204 forms the back wall of Gas
Channel 40 and is integrally attached above to the Filter section
200 roof 201 and side walls 42 and 43, ending below a short
distance from floor 203; thus presenting a space through which the
on-moving gas stream, following the direction indicated by arrow
45, turns into the Filter section 200 combination fluid sump/gas
stream entry plenum 217; the gas stream then moves upwards through
the Filter section 200 media bed 206, etc. as described prior.
[0051] As described prior, overflow drain 216 removes excess water
from the Filter section 200 sump 217 and sends it into a waste
water drain, thus preventing a backup of the treatment water from
the Filter section 200 into the Gas Channel 40.
[0052] A control panel ("Panel") 47 FIG. 4 houses the electrical
and electronic components that control the electrical power cutoff,
gas stream entry fan, moisturizing, recirculation and pH management
systems; the Panel presents with a main power switch 300; a fan
switch 301; a recirculation pump indicator light 302; a flow relay
303; a power switch 304; a pH meter 305 and a timer 306. With the
main power switch 300 turned on, the treatment Unit 1 is ready to
operate. Note: because the actual flow patterns of the gas and
moisture streams as well as most of the structural components of
the treatment unit have already been described, only descriptive
text related to pH management, moisture levels and such functional
considerations follows.
[0053] Continuing with the view presented in FIG. 4, when fan
switch 301 is activated electrical current passes on into an
electrical power wire 324 to a gas stream inlet fan 307 which then
drives the gas stream into the treatment Unit's 1 gas stream inlet
101; note, the fan can alternatively be mounted in the incoming
ductwork outside said treatment unit (not shown), or housed within
the treatment Unit's 1 gas stream inlet 101.
[0054] Water from an external source (not shown) enters via a water
inlet valve 308 and thus into a fresh water line 309 where it
passes through a pressure regulator 310 then a pressure gauge 311;
at this point the water line 309 splits into two separate supplies,
one line, a Filter section 200 inlet water line 312, which always
delivers only fresh water, passes through a solenoid valve and its
associated electrical control wire 314 that is activated by the
timer 306 located in control panel 47; timer 306 is set to
intermittently spray into the Filter section 200 moisturization
chamber 207 using the Filter section 200 sprinkler sets 208
described prior; a port and valve 48 arrangement is located on
inlet water line 312 for adding inoculation material, nutrients and
other such agents to the Filter section's 200 media bed 206.
[0055] The second branch off from fresh water line 309 is a make up
water line 313 which first passes through a rotameter 315; the
rotameter 315 is adjusted after use and trial to provide a pre-set,
stable rate of flow of water to the Scrubber sump 114 from whence
the water is then drawn into a recirculation system water line 316
by a recirculation pump 317 which is activated when pump power
switch 304 is set in the on position and the signal from pump power
switch 304 is carried to the recirculation pump 317 via an electric
power line 323; after passing through the recirculation pump 317,
the water passes by a pressure gauge 318 then past a pH probe 319
that sends a signal via an electrical control wire 320 to the pH
meter 305 in control panel 47; continuing past the pH probe 319,
the water passes through a flow transmitter 321 the signal from
which passes via an electrical control wire 322 sequentially into
indicator light 302, flow relay 303 and thus to pump power switch
304. Flow transmitter 321 serves as a fail safe device and should
the water level in the system fall below a critical level, the flow
transmitter's 321 altered signal intensity reaches the flow relay
303, which in turn will trip the pump power switch 304, thus
turning off the recirculation pump 317 and preventing damage to
same; having passed by flow transmitter 321, the water next passes
a port and valve 49 located on recirculation line 316; port and
valve 49 serve to allow addition of inoculant material, nutrients
and other such agents to the scrubber's 100 media bed 103 as
needed; finally, the pH corrected water is delivered to the
Scrubber section's 100 internal sprinklers 105, the placement of
which was described prior.
[0056] Because the Scrubber section 100 uses water from the
Scrubber sump 114 mixed with some fresh water to maintain an
optimal pH in the Scrubber section 100 media bed 103, provision is
made for some excess water to escape via an overflow drain system
comprising an overflow drain 116 and an overflow drain line 325.
Overflow drain line 325 has a trap 326 for the prevention of back
flow into the Scrubber section 100 sump 114.
[0057] Both Scrubber section 100 and Filter section 200 sumps 114
and 217 have access to a main drain line 327 FIG. 4 that exits into
a general drain line (not shown); should need arise to drain the
system entirely, opening valve 118 drains the Scrubber sump 114;
Filter drain 216 is continuously open and has a trap 329 to prevent
backflow into the Unit 1, although an optional valve closure could
be used to eliminate the need for provision of a trap on drain line
327.
[0058] Note: although they are not part of the control system,
exhaust stacks 214 (represented by arrows indicating the final
direction of the gas stream flow) are shown for purposes of
orientation.
[0059] A differential pressure gauge array 330, for the Scrubber
section 100, which serves to register the pressure differential at
the inlet and exit peripheries of the media bed 103, comprises an
externally visible differential pressure gauge attached to a pair
of pressure sensitive probes 51 and 52, one of which probes 51 is
situated in Scrubber 100 air entry plenum 102 and the other of
which probes 52 is situated in the moisturization chamber 107, thus
bracketing the media chamber 103 of the Scrubber 100 and allowing
determination of and serving warning of bed-compaction or other
such problems if the inlet and exit pressure differential becomes
too great.
[0060] A differential pressure gauge array 331, for the Filter
section 200, which serves to register the pressure differential at
the inlet and exit peripheries of the media bed 206 comprises an
externally visible differential pressure gauge having a pair of
pressure sensitive probes 53 and 54, one of which probes 53 is
situated in Filter 200 air entry plenum 217 and the other of which
probes 54 is situated in moisturization chamber 207, thus
bracketing the media chamber 206 of the Filter 200 and allowing
determination of and serving warning of bed-compaction or other
such problems if the inlet and exit pressure differential becomes
too great.
* * * * *